Patients with transthyretin amyloid cardiomyopathy who were not taking transthyretin stabilizers at the start of treatment appeared to benefit from the investigational drug eplontersen, while those already on stabilizers did not show the same effect, according to a secondary analysis of the phase 3 CARDIOTTRansform trial presented at the 2026 European Society of Cardiology Congress.
The findings, published online in Nature Medicine, examined whether background use of transthyretin stabilizers influenced the response to eplontersen, an antisense oligonucleotide designed to reduce production of transthyretin protein. The analysis suggests that the drug's beneficial effect was confined to the subgroup of patients who were not on stabilizers at baseline, raising questions about how the two treatment approaches interact in clinical practice.
Transthyretin amyloid cardiomyopathy is a progressive condition in which misfolded transthyretin protein accumulates as amyloid deposits in the heart muscle, leading to heart failure and reduced survival. Stabilizers such as tafamidis work by binding to the transthyretin tetramer and preventing its dissociation into amyloidogenic monomers, while eplontersen targets the underlying production of the protein at the RNA level.
The CARDIOTTRansform trial is a randomized, controlled study evaluating eplontersen in this patient population. This secondary analysis specifically compared outcomes between participants who were receiving transthyretin stabilizers as background therapy and those who were not. The results indicated that the clinical benefit of eplontersen was observed only in the group without stabilizer use, whereas no additional benefit was detected in patients already taking stabilizers.
These findings have potential implications for treatment sequencing and combination strategies in transthyretin amyloid cardiomyopathy. If confirmed, they may suggest that eplontersen is most effective when used as a first-line therapy or in patients who are not eligible for or have not yet started stabilizer treatment. The lack of observed benefit in the stabilizer group could reflect overlapping mechanisms of action, differences in disease stage, or other patient characteristics that were not fully accounted for in this secondary analysis.
Researchers involved in the study emphasized that secondary analyses of this type are hypothesis-generating rather than definitive. The primary trial results remain the basis for regulatory decisions, and further studies will be needed to clarify the optimal role of eplontersen relative to stabilizers. The findings also underscore the importance of careful patient selection and individualized treatment planning in a disease where therapeutic options are expanding.
The presentation at the ESC Congress and the simultaneous publication in Nature Medicine highlight the growing interest in RNA-targeting therapies for amyloid diseases. Eplontersen is part of a broader class of antisense oligonucleotides being developed for conditions caused by the accumulation of abnormal proteins. Its potential role in transthyretin amyloid cardiomyopathy is being actively investigated, and this secondary analysis adds important context for clinicians considering how to integrate the drug into existing treatment paradigms.
For now, the data suggest that the benefit of adding eplontersen may depend on whether a patient is already receiving stabilizer therapy. Clinicians will likely await further analyses and ongoing trials to determine the most appropriate use of this agent in the management of transthyretin amyloid cardiomyopathy.
